Generally, a vehicle air conditioner is provided with an air conditioning unit for blowing conditioned air to a passenger compartment, a seat air conditioning unit for controlling temperature of a seat where a passenger sits, and a control unit for controlling the air conditioning unit and the seat air conditioning unit, for example, referring to JP-2002-144849A.
The control unit determines the operation state (transient state or steady state) of the air conditioning unit, then changing the control state of the seat air conditioning unit according to the determined result. Thus, an excessive cooling operation and an excessive heating operation of the seat air conditioning unit are restricted when the air conditioning unit is in the steady state.
In this case, the transient state (e.g., immediately after a start of the vehicle air conditioner) means that a difference between a temperature in the passenger compartment and a setting temperature of the passenger compartment is large. In the transient state, a degree of alienation between a target blowing-out temperature TAO (calculated by control unit) of the air conditioning unit and the setting temperature of the passenger compartment is large. The steady state means that the difference between the temperature in the passenger compartment and the setting temperature of the passenger compartment becomes small with an operation of the vehicle air conditioner or the like. In the steady state, the degree of alienation between the target blowing-out temperature TAO of the air conditioning unit and the setting temperature is relatively small.
However, in the vehicle air conditioner, the control unit determines the operation state (transient state or steady state) of the air conditioning unit, then providing different control operations responding to the determined result. Therefore, in this case, the air conditioning control is complicated.